Standard atmosphere is 14.7 psi.
As for different PSI at the pitot head for different airspeeds? It's not as simple as that as it depends on altitude.
Remember that pitot pressure is TOTAL pressure, which is the sum of ram air pressure plus static pressure. Therefore total pressure will vary as both airspeed or altitude varies.
There are tables in a/c Maintenance manuals which provide various values for P and S to give corresponding altitudes and/or airspeeds.